So, I had the hair dryers out for something completely different. This is what happened.
Seriously, my kids kept at this for the better portion of an hour! They tried various balls, two at a time, small, big, heavy, light. It was so exciting to see the results of their different "air" experiments. Oh and the language!! Gravity, inertia, velocity! Oh my language! It was really great! I am always amazed at what can be taught with the most simple items.
You will need some balls (light weight, plastic ones work the best) and a hair dryer.